This invention relates generally to semiconductor structures and devices and to a method for their fabrication, and more specifically to semiconductor structures and devices and to the fabrication and use of semiconductor structures, devices, and integrated circuits that include a monocrystalline material layer comprised of semiconductor material, compound semiconductor material, and/or other types of material such as metals and non-metals. This invention more specifically relates to a structure and method for an integral matching network for stabilization and partial matching of active devices integrated into a monolithic structure.
Semiconductor devices often include multiple layers of conductive, insulating, and semiconductive layers. Often, the desirable properties of such layers improve with the crystallinity of the layer. For example, the electron mobility and band gap of semiconductive layers improves as the crystallinity of the layer increases. Similarly, the free electron concentration of conductive layers and the electron charge displacement and electron energy recoverability of insulative or dielectric films improves as the crystallinity of these layers increases.
For many years, attempts have been made to grow various monolithic thin films on a foreign substrate such as silicon (Si). To achieve optimal characteristics of the various monolithic layers, however, a monocrystalline film of high crystalline quality is desired. Attempts have been made, for example, to grow various monocrystalline layers on a substrate such as germanium, silicon, and various insulators. These attempts have generally been unsuccessful because lattice mismatches between the host crystal and the grown crystal have caused the resulting layer of monocrystalline material to be of low crystalline quality.
If a large area thin film of high quality monocrystalline material was available at low cost, a variety of semiconductor devices could advantageously be fabricated in or using that film at a low cost compared to the cost of fabricating such devices beginning with a bulk wafer of semiconductor material or in an epitaxial film of such material on a bulk wafer of semiconductor material. In addition, if a thin film of high quality monocrystalline material could be realized beginning with a bulk wafer such as a silicon wafer, an integrated device structure could be achieved that took advantage of the best properties of both the silicon and the high quality monocrystalline material.
Accordingly, a need exists for a semiconductor structure that provides a high quality monocrystalline film or layer over another monocrystallinie material and for a process for making such a structure. In other words, there is a need for providing the is formation of a monocrystalline substrate that is compliant with a high quality monocrystalline material layer so that true two-dimensional growth can be achieved for the formation of quality semiconductor structures, devices and integrated circuits having grown monocrystalline film having the same crystal orientation as an underlying substrate. This monocrystalline material layer may be-comprised of a semiconductor material, a compound semiconductor material, and other types of material such as metals and non-metals.
In semiconductor systems, output drivers are required to drive input/output devices and similar loads. In order to have efficient power transfer it is important that the impedance of the driver closely match the impedance of the load where the load is the impedance of the driven device and the impedance of the transmission line. Ideally, the driver impedance and the load impedance are identical. Therefore, high performance semiconductor devices such as Pseudomorphic High Electron Mobility Transistor (PHEMT) and Metal-Semiconductor-Field-Effect-Transistor (MESFET) and other microwave and millimeter wave devices require matching network structures to transform the intrinsic impedances of the devices to standard impedances. Typically, the intrinsic impedances must be transformed to a much larger magnitude. Generally, high power devices in particular have very low input and output impedances, typically on the order of a few ohms. Impedance matching networks are known that can transform this low impedance to a usable standard impedance, typically 50 ohms. However, these matching networks can be large and very lossy. Additionally, matching networks to achieve intermediate impedances may also be useful. Additionally, a stability network is typically required for the majority of all microwave and millimeter frequency active devices so that unconditional stability is assured. This stability network is typically an auxiliary network and requires additional components and die ;area. Accordingly, a need exists for an integrated matching and stability network that can be integrated into a compact area.